Device comprising a gaseous discharge tube



1949. F. c. VAN LOOY ET AL I DEVICE COMPRISING A GASEOUS DISCHARGE TUBEFiled March 11, 1947.

Patented Aug. 23, 1949 g UNITED STATES PATENT OFFICE DEVICE COMPRISING AGASEOUS DISCHARGE TUBE Franciscus Cornelis van Looy and PieterSchouwstra, Eindhoven, Netherlands, assignors to Hartford National Bankand Trust Company, Hartford, Conn., as trustee Application March 11,1947, Serial No. 733,750 In the Netherlands March 18, 1942 Section 1,Public Law 690, August 8, 1946 Patent expires March 18, 1962 Claims.(01. 315-243) 1 2 It is known to ignite gaseous discharge tubesoccurrence of the main discharge is also retarded, with the aid of aresonant circuit which, prior to which enables the incandescent cathode,which the ignition of the gaseous discharge tube, is trais heated fromthe outside, to attain its emission versed by a strong current whichgenerates in the temperature. The current or th auxiliary diselements ofthe circuit high voltages which may 6 charge is sufliciently high toclose the thermal be d to te t e us scha ge tube. switch whose heatingelement has a high resist- After the ignition of this tube the currentstrength ance, due to which this heating element is shortfallsconsiderably at least in a part of this circuit, circuited. If thedischarge tube is not defective, since the d scharge tube which is thenconductive the main discharge can subsequently be ignited. is connectedin parallel With a part Of the reso- 10 If this main discharge 109 notignite however, nant circuit which consequently gets out of resothecurrent of the auxiliary discharge, which ournance. The elements of thecircuit are as a rule rent has acquired a much greater strength dueproportioned in accordance with the current to the describedshort-circuit of the heating elestrength which occurs, 1. e. during thenormal merit, brings about a strong development of heat operation of thedischarge tube. in the second heating body. Consequently, after In theCase, hOWeVeI. that e d sc arge tube a certain lapse of time, thecontact of the bidoes not ignite after the device has been put undermetallic element heated by this heating body t s the strong resonant ntke ps flowin contacts with the countercontact, due to which which notonly implies an unnecessary waste of the condenser of the resonantcircuit is bridged energy but also an overcharge of the elements by apart of the choke-coil and the two heating of the circuit, due to Whichthese elements might elements of the thermal switches. Consequently,

be deteriorated. the resonant circuit is brought out of resonance Adevice is known which comprises a gaseous and an overcharge of thedevice is avoided. discharge tube having one incandescent cathode Inorder to prevent the condenser from being and two anodes, which tube isfed by an autoshunted also when the main discharge is ignited, leakagetransformer, one extremity of the secthe device comprises, in addition,auxiliary means ondary Winding of this transformer being conwhich makethe thermal switches inoperative nected to one terminal of a condenser,whereas under the action of th main discharge current.

the other extremity of this winding is connected These auxiliary meansare constituted by the to a choke-coil; the other terminal of theconinterruptor already referred to, which is condenser is connected to atapping of the chokestructed in the form of an electromagnetic switch.coil, so that this condenser and a part of the On being energised by themain discharge curchoke-coil in series with one another are conrent,said interruptor switches ofi the heating nected to the extremities ofthe secondary transelements of the thermal switches, establishing atformer winding. The circuit thus produced con- 5 the same time a directconnection between the stitutes a resonant circuit. One of the anodes oflast-mentioned anode and that extremity of the the gaseous dischargetube is directly connected secondary winding of the transformer which isto that extremity of the transformer which is conconnected to thechoke-coil. nected to the condenser, whereas the other anode Thecondenser is bridged and hence the resois connected to that extremity ofthe choke-coil nant circuit is brought out of resonance in this which isremote from the transformer through known device by the current of theauxiliary disthe intermediary of an interruptor and the heatchargebetween the two anodes of the discharge ing elements of two thermalswitches. The cathtube. If this auxiliary discharge is not estabode ofthe gaseous discharge tube is connected to lished (which may be due, forexample, to a bad the middle of the secondary winding of thetranscontact or to a crack in the supply conductor or former. to thecircumstance that it has been omitted to When this device is put undertension, a high place the discharge tube in the device), the resovoltageis set up between the two anodes of the nant state and the drawbacksinvolved subsist, gaseous discharge tube by means of the resonanthowever, after the device has been switched in. circuit, said voltagebringing about an auxiliary Moreover, this known device which utilisestherdischarge between the anodes. The intensity of mal switches and, inaddition, auxiliary means to this discharge is initially small, sincethe auxiliary render these switches inoperative under the actiondischarge path has connected in series with it the of the dischargecurrent, is very complicated. two heating elements of the said switches,one of The present invention relates to a device comwhich has a highresistance. Consequently, the prising a gaseous discharge tube which, ifnecesvoltageless.

sary with the interposition of an impedance, bridges a part of aresonant circuit comprising a series-connected inductance and acapacity. The term resonant circuit is to be understood to mean not onlya circuit whose capacitative impedance is exactly equal to the inductiveimpedance, since these impedances will asa rule be difierent from eachother. It is only necessary that the circuit is so tuned to thefrequency of the feeding current that in that portion of the circuitwhich is shunted by the discharge tube a voltage is generated which issufficiently high for a normal ignition of the gaseous discharge tube.The term gaseous discharge tube has to be understood to mean not only adischarge tube filled with one or more gases, but also a tube in whichthe discharge takes place in an atmosphere consisting of vapour or amixture or gas and vapour.

The present invention has for its-purpose to realise the knownprinciple, accordingto which a too long continuation of atoo strongcurrent in the resonant circuit in the case of non-ignition of thedischarge tube is avoided, in a better and simpler manner than is knownhitherto.

According to the invention, the circuit is brought out of resonance withthe aid of a timelag switch whose energising element either is cated inthe resonant circuit, or is connected in parallel with a part of theresonant circuit, said 11 switch being constructed in such manner thatthe current which has to flow through the energising element to actuatethe switch is higher than that which flows during normal operation ofthe discharge tube, but at most equal to the current which flows throughthis element when the tube is not ignited, while the switch, once becomeoperative, keeps the position then occupied until the device is madevoltageless.

When the device is switched-in while the dis 1 charge tube is defective,so that it cannot ignite,

the state of resonance continues only during the time-lag of the switch;after expiration of this time-lag the switch, due to the latter beingclosed or opened, brings the circuit out of resonance so that thecurrent strength is reduced to a value which is not injurious to theelements constituting the circuit. If the switch were constructed insuch manner that it would return to its initial position with thissmaller current strength, the state of resonance and the undesirablestrong current involved in the case of non-ignition of the dischargetube would be re-established. This drawback is obviated due to theswitch being so constructed that, once become operative (i. e. after ithas been closed or opened), it keeps its position then occupied untilthe device is made When a new discharge tube is substituted for thedefective one, the device is then immediately ready again for its normalfunction.

Since the switch is actuated by the resonant current itself (or, if theenergising element of the switch is connected in parallel with a part ofthe resonant circuit, by a current proportional to the resonant current)it will perform its function not onlywhen the discharge tube does notignite due to a cause which resides in the tube itself, but for examplealso when the tube is not tinues for a suificiently long time to ignitethe If the ignition is efiected in discharge tube.

time, the energising element of the switch is then traversed only by acurrent which cannot actuate the switch. Particular auxiliary meanswhich make the switch inoperative under the action of the dischargecurrent flowing through the discharge tube are here consequentlysuperfiuous, which renders the device also simpler than the known deviceabove-described.

The resonant circuit may be brought out of resonance in differentmanners. The switch may bridge or switch off, for example, a portion ofthe resonant circuit or add an impedance to the resonant circuit. Thebridging may be effected by means of an auxiliary circuit which is alsoconnected in parallel with the discharge tube. When the discharge tubeignites, the discharge path which has then become conductive brings theresonant circuit out of resonance, whereas, if the discharge tube doesnot ignite, this is effected by means of the auxiliary circuit which isconnected in parallel with the discharge tube.

In addition to the resonant current, the. device may also be traversedunder certain conditions by other currents of impermissible strength andduration. The initially equal emissive power of the electrodes may, forexample, have changed by the end of the life of the tube in such mannerthat the current in a definite halfcycle of the feeding alternatingcurrent is considerably smaller than in the following halfcycle. Thisimplies the occurrence of a directcurrent component with the result thata chokecoil which is connected in series with the tube has a smallerimpedance and consequently passes a stronger current than when analternating current without direct-current component flows. In this casethe choke-coil and also other elements of the device are subject to astronger heating than in normal operation.

According to one embodiment of the invention, in this case also anydeterioration of the elements of the device may be prevented byconnecting the energising element of the switch, at least during thenormal operation, in series with the discharge tube. It is thus achievedthat the switch is actuated not only when the tube does not ignite butalso when a direct-current component of impermissible strength occurs.

If it is desired with the aid of the precautions taken in accordancewith the invention to protect the device also against such undesirablecurrent strengths which occur after the ignition of the discharge tube,it is possible by a suitable choice of the construction of the switch todetermine the current strength which is still permissible. In this casethe switch will be, for example, such that the minimum current which hasto flow through the energising element to actuate the switch is at theutmost 50% or 30% higher than the current which flows through theenergising element of the switch in normal operation of the dischargetube.

In some embodiments of the invention it may occur that, after the switchhas been actuated, the current flowing through the energising element ofthe switch is too small to keep the switch in the position thenoccupied. Consequently, the position of too high current strength wouldbe re-established, whereupon the switch would be actuated again, whichwould continuously be repeated. This drawback may be obviated byproviding the switch with an auxiliary energising element which is nottraversed by current until the switch has been actuated by the main tubedoes not ignite.

amaoco energising element. To this end, said auxiliary energisingelement may be included, for example, in the auxiliary circuit which asa result of the actuation of the switch is connected in parallel with apart of the resonant circuit. When use is made of a bimetallic switch,each of the two contacts may be secured, for example, to a bimetallicstrip which comprises a heating" element. In this case one heatingelement is included in the resonant circuit, whereas the second heatingelement is included in an auxiliary circuit which may bridge thedischarge tube.

The invention will be explained more fully by reference to theaccompanying drawing showing diagrammatically, by way of example,several embodiments thereof and in which 7 Figure 1 illustrates one formof circuit arrangement in accordance with theinvention,

Figure 2 illustrates anothercircuit arrangement in accordance with theinvention,

Figure 3 illustrates a further modification in accordance with theinvention and Figure 4 illustrates still another embodiment of theinvention.

In Fig. l, idesignates a discharge tube filled with gas and vapour, forexample a low-pressure mercury vapour discharge tube, whose wall may becovered with substances which become lumi nescent under the action ofthe mercury vapour discharge. This tube bridges a condenser 3 with w theinterposition of a choke-coil 2, said condenser being connected to asource of alternating current of normal frequency via a choke-coil 4 andterminals 5 and S. The voltage of this source of current is lower thanthe ignition voltage of the i tube. The choke-coil 4 and the condenser 3have such values that a voltage is set up at the terminals of thecondenser, which is higher than the voltage of the source of supply andsulficiently high to ignite the tube. The discharge tube may containeither cold or incandescent electrodes. According to Fig. 1, tube Icontains two incandescent electrodes l and 8 which are fed from twoheating windings 9 and III of a transformer, the primary winding ofwhich is conl stituted by the choke-coil 4.

The circuit constituted by the series connection of the choke-coil 4 andthe condenser 3, after the terminals 5 and 6 of the device have beenconnected to the source of alternating current, is traversed by a strongcurrent which serves for quick heating of the incandescent electrodesvia the heating windings 9 and I0 and which also ignites the tube. Afterthe. ignition of the. tube, the high current flowing through l.

said circuit falls considerably, though the current which flows throughthe choke-coil 4 does, not become the same as the current which flowsthrough the condenser 3. i

The heating element II of a bimetallic switch I 2 is connected in serieswith the circuit 4-3 and the discharge tube I. The bimetallic element I3and the contact piece I4 of this switch are connected to the extremitiesof the choke-coil 4, so that the switch short-circuits the latter in theposition of the bimetallic element I3 which is indicated in dotted line.The bimetallic, switch is such that it keeps open with the currentstrength which occurs when the tube is ignited and that its contactsengage each other with a current strength which is higher than thecurrent which flows when the tube is ignited and smaller than thecurrent which news when the At the same time it is ensured that thecurrent which flows through the heating: element I I when the choke coil4. is short,- circuited keeps the contacts of the switch closed.

In a concrete case the bimetallic switch enclosed in an evacuated littletube was so constructed that its contacts closed with any current higherthan 195 milliamps. and in the hot condition of the switch kept closedwith currents higher than 180 milliamps. The contacts are closed'morequickly, according as the current is higher than the said value. Priorto the ignition, which in the normal condition of tube I takes placeWithin one second, and with a terminal voltage of 220 volts of thesource of supply of cycles/sec. the heating element II, the chokecoil 4'and the condenser 3 were traversed by a current of 519 milliamps. Withthis current strength the bimetallic switch has a closing time of 18seconds, so that the switch was not actuated during theperiod ofignition of the tube. During this period the voltage set up at the ter--minals of the condenser 3 and also at the electrodes ofthe tube was 390volts, whereas 2. volt age of 1% volts was set up at the choke-coil 4.After the ignition, i. e. in less than 1 sec... the current flowingthrough the choke-coil 4 decreased to 145 milliamps., the currentflowing through the condenser 3 to 320 milliamps., the

voltagesct up at the choke-coil 4 to 78 volts and the voltage set up atthe condenser 3 to 240 volts, while the current flowing through the tubeI and thec'hoke-coil 2 now attained 250 milliamps. and the voltage ofthe tube 105 volts.

When the tube doesnot ignite, the above stated high currents andvoltages subsisted for 13 sec onds, until the bimetallic switch shortcircuited the choke-coil 4. Subsequently, the current flowing throughthe heating element I I and through the condenser 3 decreased to 285milliamps. and the voltage set upat'the condenser 3 to about 220 volts.Since this current strength is higher than the minimum current strengthrequired to main tain the switch closed, this condition of decreasedcurrent subsisted. After the device had been switched off and thedefective tube replaced, the bimetallic switch was cooled down, so that'the device was again in its original condition as soon as it wasswitched-in anew.

The circuit described offers the additional advantage'that a too highcurrent strength brought about by other causes may also be decreased.This case may occur when the tube takes up currents of different valuesin successive halfcycles due to the emissive power of the incandescentelectrodes having become different. This phenomenon implies theoccurrence of a directcurrent component which prernagnetises the ironcores of the choke-coils 2 and t and brings about higher iron losses,higher operating temperatures and a lower value of the inductance of thechokecoils, as well as a stronger current through the whole device.

If the current strength in the heating element II exceeds a value ofmilliamps., the bimetallic switch short-circuits the choke-coil s with adefinite time-lag. After this short-circuiting the tube may extinguish,which corresponds to the state of the not igniting tube and theshortcircuited choke-coil 4. Consequently, this shortcircuit alsosubsists and the device is automatieally ready for use again after ithas been switched off and the tube changed. It is, however,al'so-possible after the choke-coil t has been short-circuited that thetube keeps burning at thevoltage of 220 volts of the source of suppiy.

Inth-is-case the heating element II is traversed by a current of 235milliamps., so that this condition subsists with a current through thetube of 135 milliamps. The tube is nowburning at approximately half thecurrent, gives little light and consequently attracts the notice. Inthis case also the device is ready for further operation aftersuppression of the disturbance.

It is evident that it is not necessary for the bimetallic switch toshort-circuit the choke-coil, since the latter may also be bridged by itvia a resistance.

Fig. 2 shows a device which differs from that shown in 1 in so far asthe heating element is connected in parallel with the choke-coil 4 andthe capacity 3 is constituted by the parallel connection of twocondensers 3I and 32, of which condenser 32 is switched oil when tube Idoes not ignite. The contacts of the bimetallic switch are then openedby the high current. The operation of this device corresponds to that ofthe device shown in Fig. 1.

It is evident that the increased current strength due to a rectifyingaction of the tube may here also be reduced to a harmless value. In Fig.2, the incandescent electrodes and their circuits are omitted forsimplicitys sake. Identical elements are indicated in the figures by thesame numerals.

Fig. 3 shows a device in which the resonant circuit is constituted bythe series-connection of the choke-coils 4 and I6 and the condenser 3.Tube I bridges the choke-coil It and the condenser 3. Any availableincandescent electrodes of the tube may be supplied from a transformer,the primary winding of which is constituted by the choke-coil It. Inthis device the current which flows through the choke coil 4 before andafter the ignition of the tube does not change appreciably, so that alimitation of this current if the tube does not ignite is superfluous.However, the current which flows through the part I 63 of the circuit,which is bridged by the tube, changes considerably.

By including the heating element II of a bimetallic switch in that partof the circuit which is bridged by the tube and by connecting thebimetallic element l3 and the contact piece I4 of the bimetallic switchto the extremities of the choke-coil IE, it may be achieved that thecurrent which flows through the parallel branch when the tube is notignited is decreased to a permissible value. As it appears already fromthe devices before described, it must then be ensured that, after thechoke-coil I6 has been short-circuited, a current flows which issufficiently high to maintain the contacts of the switch in closedposition.

In a concrete case the current which flowed through the choke-coil 4prior to the ignition of the tube was 126 milliamps. and the currentwhich flowed through the heating element I I, the choke-coil I 6 and thecondenser 3 2226 milliamps. After the ignition these currents were 225milliamps. and 56 milliamps. respectively. After the choke-coil I hasbeen short-circuited, the current which flowed through the elements 4,II, and 3 was 123 milliamps. The bimetallic switch was so constructedthat its contacts were kept closed with security with currents higherthan 80 milliamps.

It is evident that the switch, instead of short-mcircuiting thechoke-coil I6, may alternatively bridge the latter or a part thereof viaan impedance. In addition, this switch may bridge the condenser 3 withor without the interposition of impedances, switch on a part of thecapacity of this condenser and/or connect a condenser in parallel withthe condenser 3 or with one or more elements of the device.

Fig. 4 shows a device which differs from that shown in Fig. 1 in thatthe incandescent electrodes are connected in series with the auxiliaryelements of the circuit. For this purpose the incandescent electrode 8is included between the condenser 3 and the choke-coil 4, the choke-coil2 of Fig. 1 comprising two windings 2| and 22 which are arranged on thesame iron core, which have approximately the same number of turns andwhich are connected to each other via the incandescent electrode 1 insuch manner that the series current flowing through these windings priorto the ignition of the tube I generates magnetic fields which counteracteach other so as to practically neutralise each other. During the normaloperation, however, this choke-coil operates in substantially the samemanner as the choke-coil 2 in the circuit of Fig. 1.

In series with the circuit comprising all the circuit elements of thedevice and in series with the tube is included a heating element I I ofa bimetallic switch I2, for example the connection between thechoke-coil 4 and the electrode 8 as is shown in the figure. The switchI2 comprises two bimetallic strips I3 and I8. The fixed extremity of thebimetallic strip I3 is connected to a point between the heating elementI I, which cooperates with this strip, and the electrode 8, whereas themovable extremity comprises a contact piece II. lhe other bimetallicstrip I8 comprises as its movable extremity a countercontact piece I4and is connected through a separate heating element I9 to a pointlocated between the electrode I and the Winding 22.

This device operates as follows:

When the device is connected to the source of alternating current, astrong current which is substantially determined by the choice of thecapacity of the condenser 3 and the inductance of the choke-coil 4 flowsthrough the series circuit 2I1223--8I I4. This current heats theelectrodes 1 and 8 and brings about a potential difference across thecondenser 3, which is also set up substantially unchanged at the tube Iand ignites the latter. After the ignition of the tube, the high currentflowing through the said circuit falls considerably; in this case thecurrents flowing through the windings 2|, 22 and through the dischargetube I are relatively different.

If the tube does not ignite, the heating element II heats the strip I3so strongly that the contact piece I l engages the countercontact I4,thus establishing a direct connection between the electrodes via theother heating element I9, due to which the undesirable high currentthrough the heating element II is considerably reduced. Consequently,the strip I3 is heated less strongly so that it would be withdrawn againfrom the contact piece I4. The heating element I9 is, however, soproportioned as to cause the strip I8 and the contact piece I4 in thedirection of the contact piece I1 to withdraw more quickly than thestrip I3 and the contact piece I! retire, so that the contact betweenthe contact pieces I! and I4 subsists until the device is switched offfrom the source of supply.

This device also permits of reducing an undesirable high currentresulting from the occurence of a direct-current component.

The two bimetallic strips I3 and I8, together with their heatingelements II and I9, may be so proportioned as to be equal to each other.

In a concrete case the elements of the device were so chosen that, whenthe tube does not ignite or does not yet ignite, a current of about 450milliamps. flowed through the heating element ll. During the normaloperation of the tube this current was 150 milliamps. and could assume astrength of from 250- to 400 milliamps. when a direct-current componentoccurred. When the contact pieces l4 and i1 engaged each other, thecurrent through the heating element l l was about 140 milliamps. whereasthe heating element l9 was then traversed by a current of 330 milliamps.

The two bimetallic strips l3 and i8 and their heating elements H and [9were equally proportioned and exhibited the following characteristic:closure at 450 milliamps. within seconds, with 250 milliamps. within 120seconds, no closure with 185 milliamps. or less.

If the tube after being switched-in doesnot ignite within 20 seconds, ora direct-currentcomponent greater than 185 milliamps. occurs, thecontacts l4 and H are closed. This contact keeps closed until the deviceis switched off, since a the condition that the strip 3 with 330milliamps. is heated up by the element I!) more quickly than the stripl3 cools down with a sudden fall of the current through the element H toI40 milliamps, is largely satisfied.

Whenever in the explanation of the devices shown in the figuresreference is made to bimetallic switches, it is possible for the purposeof bringing about the desired changes to utilise, instead of theseelements, other known means operating with the required time-lag, forexample electro-magnetic switches.

What we claim is:

1. An alternating current electrical circuit arrangement comprisingcapacitive and inductive elements coupled in series arrangement andhaving reactance values to produce a resonance circuit, a gaseouselectric discharge tube coupled in shunting relationship with one ofsaid elements, and a time delay switch comprising an actuating memberand switch contact members, said switch contact members being coupled toone of said elements to vary the reactance value thereof in said seriescircuit while maintaining said series circuit continuous, and saidactuating member being coupled to saidv series circuit and beingresponsive to resonance current flow in said series circuit to actuatesaid switch contact members and being further responsive to nonresonancecurrent flow in said series circuit to maintain said switch contactmembers in actuated position.

2'. An alternating current electrical circuit arrangement comprisingcapacitive and inductive elements coupled in series arrangement andhaving reactance values to produce a resonance circuit, a gaseouselectric discharge tube coupled in shunting relationship with one ofsaid elements, and a time delay switch comprising an actuating memberand switch contact members, said switch contact members being coupled toone of said elements to vary the reactance value thereof in said seriescircuit while maintaining said series circuit continuous, and saidactuatin member being connected in series with said series circuit andbeing responsive to resonance current flow in said series circuit toactuate said switch contact members and being further responsive tonon-resonance current flow in said series cir- I0 cult to maintain saidswitch contact members in actuated position.

3. An alternating current electrical circuit arrangement comprisingcapacitive and inductive elements coupled in series arrangement andhaving reactance Values to produce a resonance circuit, a gaseouselectric discharge tube coupled in shunting relationship with one ofsaid elements, and a time delay switch comprising an actuating memberand switch contact members, said switch contact members being coupled toone of said elements to vary the reactance value thereof in said seriescircuit while maintaining said series circuit continuous, and saidactuating member being connected in shunt with one of said elements andbeing responsive to resonance current flow in said series circuit toactuate said switch contact members and being further responsive tonon-resonance current flow in said series circuit to maintain saidswitch contact members in actuated position.

4. An alternating current electrical circuit arrangement comprisingcapacitive and inductive elements coupled in series arrangement andhaving reactance values to produce a resonance circuit, a gaseouselectric discharge tube coupled in shunting relationship with one ofsaid elements, and a time delay switch comprising an actuating memberand switch contact members, said switch contact members bridging one ofsaid elements to vary the reactance value thereof in said seriescircuit, and said actuating member being coupled to said series circuitand being responsive to resonance current flow in said series circuit toactuate said switch contact members and being further responsive tononresonance current flow in said series circuit to maintain sald'switchcontact members in actuated position.

5. An alternating current electrical circuit arrangement comprisingcapacitive and inductive elements coupled in series arrangement andhaving reactance values to produce a resonance circuit, one of saidelements comprising a first and a second component, a gaseous electricdischarge tube coupled in shunting relationship with one of saidelements, and a time delay switch comprising an actuating member andswitch contact members, said switch contact members being coupled to oneof said elements to disconnect one of said components and thereby varythe reactance value of said element in said series circuit whilemaintaining said series circuit continuous, and said actuating memberbeing coupled to said series circuit and being responsive to resonancecurrent flow in said series circuit to actuate said switch contactmembers and being further responsive to non-resonance current flow insaid series circuit to maintain said switch contact members in actuatedposition.

6. An alternating current electrical circuit arrangement comprisingcapacitive and inductive elements coupled in series arrangement andhaving reactance values to produce a resonance circuit, a gaseouselectric discharge tube coupled in shunting relationship with one ofsaid elements, and a time delay switch comprising an actuating memberand switch contact members, said switch contact members bridging one ofsaid elements to vary the reactance value thereof in said seriescircuit, and said actuating member being connected in series with saidseries circuit and being responsive to resonance current flow in saidseries circuit to actuate said switch con- 11 tact members and beingfurther responsive to non-responsive current flow in said series circuitto maintain said switch contact members in actuated position.

7. An alternating current electrical circuit arrangement comprising acapacitive element, a first inductive element comprisin a first windingconnected in series circuit with said capacitive element and second andthird windings inductively coupled to said first winding, saidcapacitive and inductive elements having reactance values to produce aresonance circuit, a gaseous electric discharge tube comprising twofilamentary electrodes and having one electrode thereof connected to oneterminal of said capacitive element, a second inductive elementinterconnecting the other electrode of said tube and the other terminalof said capacitive element, means to couple said electrodes to saidsecond and third windings, and a time delay switch comprising anactuating member and switch contact members, said switch contact membersbridging said first winding, and said actuatin member being connected inseries with said first winding and said capacitive element and beingresponsive to resonance current flow in said series circuit to actuatesaid switch contact members to a closed position and being furtherresponsive to non-resonance current flow through said capacitive elementto maintain said switch contact members in closed position.

8. An alternating current electrical circuit arrangement comprising acapacitive element having a first component and a second component, afirst inductive element connected in series circuit with said capacitiveelement, said capacitive and inductive elements having reactance valuesto produce a resonance circuit, a gaseous electric discharge tubecomprising two electrodes and having one electrode thereof connected toone terminal of said capacitive element, a second inductive elementinterconnectin the other electrode of said tube and the other terminalof said capacitive element, and a time delay switch comprising anactuating member and switch contact members, said switch contact membersbeing connected in series with one of said capacitive elementcomponents, and said actuating member being connected in shunt with saidfirst inductive element and being responsive to resonance current flowin said series circuit to actuate said contact members to an openposition and being further responsive to non-resonance current flowthrough said series circuit to maintain said con tact members in openposition.

9. An alternating current electrical circuit arrangement comprising inseries circuit arrangement a capacitive element and an inductive elementhaving a first and second component, said capacitive and inductiveelements having reactance values to produce a resonance circuit, agaseous electric discharge tube connected in shunt with said capacitiveelement and one of said inductive element components, and a time delayswitch having an actuating element and switch contact members, saidswitch contact members shunting said one inductive element component,and said actuating element being connected in series with saidcapacitive element and said one inductive element component and beingresponsive to resonance current flow in said series circuit to actuatesaid contact members to a closed position and being further responsiveto nonresonance current flow through said series circuit to maintainsaid contact members in closed position.

10. An alternating current electrical circuit arrangement comprising agaseous electric discharge tube having two filamentary electrodes, aseries circuit comprising in the order named a first inductiveelement,one of said electrodes, a capacitive element, a second inductiveelement, the other of said electrodes and a third inductive element,said first inductive element and said capacitive element having reactivevalues to produce a resonance circuit, said second and third inductiveelements being mutually coupled to produce magnetic fields whichsubstantially counteract each other during resonance current flow insaid series circuit, and a time delay switch comprising two contactmembers, a first actuating element for one of said contact members and asecond actuating element for the other of said contact members, saidcontact members being connected in shunt with said tube, said firstactuating element being connected in said series circuit and beingresponsive to resonance current flow to close said contact members andsaid second actuating element bein connected in series with said contactmembers and being responsive to non-resonance current flow in saidseries circuit to maintain said contacts in closed position.

FRANCISCUS CORNELIS VAN LOOY. PIETER SCHOUWSTRA.

REFERENCES CITED The following references are of record in the file ofthis patent:

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